Green house gases
•The primary components of Earth’s atmosphere, N2 and O2 do not
have absorption in the IR wavelength range, therefore, do not have a
significant role in setting the surface temperature of the planet…
•Greenhouse gas are efficient in absorbing IR light…
•The most important greenhouse gases are:
•H2O – Water vapor.
•CO2 – Carbon Dioxide
•CH4 – methane
•The most abundant greenhouse gas in Earth’s atmosphere is
water vapor. Most of the greenhouse heating of Earth’s
atmosphere is due to Water vapor absorption of IR radiation
emitted by Earth, and then transferring the energy to the
surrounding air molecule
GHG GWP in 100 years
HFC 140 to11,700
Global-warming potential (GWP) is a relative measure of how
much heat a greenhouse gas traps in the atmosphere. It
compares the amount of heat trapped by a certain mass of the
gas in question to the amount of heat trapped by a similar mass
of carbon dioxide. A GWP is calculated over a specific time
interval, commonly 20, 100 or 500 years. GWP is expressed as a
factor of carbon dioxide (whose GWP is standardized to 1). For
example, the 20 year GWP of methane is 72, which means that if
the same mass of methane and carbon dioxide were introduced
into the atmosphere, that methane will trap 72 times more heat
than the carbon dioxide over the next 20 years.
The GWP depends on the following
• The absorption of infrared radiation by
a given species.
• The spectral location of its absorbing
• The atmospheric lifetime of the species
Green house effect is due to Green house gases.
• Volcanic out gassing.
• burning of organic matter.
• Respiration by living organisms.
Properties CO2 :
• It is a colorless gas.
• It condenses into solid form (dry ice) at -78 C in atmospheric
• Condenses into liquid at -57 C at pressure above 5.1
• It is Highly soluble in water.
•it exists in liquid, solid, and gaseous states.
•At room temperature, it is a tasteless and odorless liquid
•It is referred to as the universal solvent.
•Water has a neutral pH.
•anaerobic decay of organic matter
•rice cultivation etc.
•Methane is a colourless, odourless gas which is lighter than air.
•It is a non-polar molecule and is insoluble in water.
•It dissolves in non-polar solvents like alcohol, carbon tetrachloride, etc.
•It is a renewable source of natural gas since it comes from decaying garbage.
•Methane burns in air with a blue flame.
•Methane is quite unreactive, except with fluorine, chlorine, etc. With these it
undergoes substitution reactions.
•Methane undergoes oxidative pyrolysis to form carbon monoxide
2006–2009 methane concentration in the upper troposphere
•Nitrous oxide is emitted by bacteria in soils and oceans.
•Agriculture is the main source of human-produced nitrous oxide.
•The livestock sector (primarily cows, chickens, and pigs) produces 65%
of human-related nitrous oxide.
•Industrial sources make up only about 20%
•Nitrous oxide is commonly prepared by deliberate heating of
ammonium nitrate, which decomposes into nitrous oxide and water
•Nitrous oxide commonly known as "laughing gas", has been used
since long period to relieve pain and anxiousness during medical